Perceptual color scales for univariate and bivariate data display

Ten univariate and six bivariate color-encoding schemes were created within the perceptually uniform CIELAB color space. The effectiveness of these color scales was evaluated in three psychophysical experiments. Experiments I and II tested the ten univariate scales and Experiment III tested the six bivariate schemes. Experiments I and III were paired-comparison experiments in which observers judged the utility of the various renderings. Experiment II evaluated the scales by having observers judge the values of indicated points in the images. Experiments I and II demonstrated that the performance of Spectral L* and the three diverging color scales were significantly better than the other six. Experiment III showed that the constant hue plane scheme had a better rendering performance than the double cone and cylinder schemes. In both the double cone and cylinder schemes, the narrow hue range performed better than the one with wide range. There was no strong image dependency for univariate scales, but there was for the bivariate schemes.